European Patent 0 185 856 B.sub.1 discloses a known instrument panel formed by two panel parts each having walls forming a duct. The duct connects components of the ventilation and heating system, such as connections between a heating or air-conditioning system and the corresponding outlet nozzles. A disadvantage of known instrument panels is that the ducts are formed by thin, essentially vertical walls extending from the panel parts. The panel parts have to be accurately shaped so that the corresponding contact surfaces of the panel parts rest flush against one another. Furthermore, additional assembly is required to insert the individual components of the heating and ventilation system in specifically provided cutouts.